Underwater well enclosing capsule and service chamber



Nov. 21, 1967 J. E. BLANDING ETAL 3,353,354

UNDERWATER WELL ENCLOSING CAPSULE AND SERVICE CHAMBER 17 Sheets-Sheet 1Filed April 26, 1962 their ATTORNEYS Nov. 21, 1967 J. E. BLANDING ETALFiled April 26, 1962 UNDERWATER WELL ENCLOSING CAPSULE AND SERVICECHAMBER 17 Sheets- Sheet 2 "II II! JAMES VINCE TINVENTORS' N HARRING NEDMUND c. TRAGESER 8T0 JOHN E. BLANDING- their ATTORNEYS J. E. BLANDING'ETAL 3,

UNDERWATER WELL ENCLOSING CAPSULE AND SERVICE CHAMBER Filed April 26,I962 17 Sheets-Shet s 1 L F/Gf 3 l f 64 I lllllllllllllllll l i llllilml 27 57 ll I .ZfiyfifJAMES vlucslwm flzc p fi smu EDMUND c. TRAGESER aJOHN E. BLANDING F I K v lid. I I W,

Jmi h AT l Nov. 21 1967 J. E. BLANDING ETA L 3,

UNDERWATER WELL ENCLOSING CAPSULE AND SERVICE CHAMBER Filed April 26,-1962 17 Sheets-Sheet 4 IN VEN TORS.

JAMES VINCENT HARRINGTON, EDMUND C. TRAGESER 8 JOHN E. BLANDING theirATTORNEYS.

1967 I J. E. BLANDING ETAL UNDERWATER WELL ENCLOSING CAPSULE AND SERVICECHAMBER l7 Sheets-Sheet 5 Filed April 26, 1962 w 5T8 MW e Mmmm Q SD & VEN N A TML m5 M E M1 VD S W C. .M

t i ATTORNEYS.

J. E. BLANDING ETAL l7 Sheets-Sheet 6 UNDERWATER WELL ENCLOSING CAPSULEAND SERVICE CHAMBER Nov. 21, 19 67 Filedflpril 26, 1962 EI-H L -64. lll

I; I v

INVENTORS. JAMES'VINCENT HARRINGTON, EDMUND c. TR'AGESER 8.

JOHN E. BLANDING h ATTORNEYS.

J. E. BLANDING ETAL 3,353,364

17 Sheets-Sheet 7 0 0 0 in: P wn a W INVENTORS JOHN. E. BLANDI NG,

UNDERWATER WELL ENCLOSING CAPSULE AND SERVICE CHAMBER Nov. 21, 1967Filed April 26, 1962 EDMUND C. TRAGESER a V JAMES VINCENT HARRINGTONtheir 7 ATTORNEYS Nov. 21, 1967 J.E. BLANDING ETAL 3,353,364

UNDERWATER WELL ENCLOSING CAPSULE AND SERVICE CHAMBER Filed A ril 26,1962 1-7 Shqets-Sheet s EDMUND C. TRAGESER 8: JAMES VINCENT HARRINGTON M4 M, @MJ

' iheir ATTORNEYS 1967 J. E. BLANDING ETAL 3,353,364

UNDERWATER WELL ENC LOSING CAPSULE AND SERVICE CHAMBER Filed April 26,1962 17 Sheets-Sheet 9 FIG. /2

I NVENTORS JOHN E; BLANDING,

EDMUND QTRAGESER & JAMES VINCENT HARRINGTON the r ATTORNEYS 1967 J, E.BLANDING ETAL 3,353,364

UNDERWATER WELL ENCLOSING CAPSULE AND SERVICE CHAMBER Filed April 26,1962 17 Sheets-Sheet 1O FIG. /4

INVENTORS JOHN E. BLANDING, EDMUND C. TRAGESER 8 JAMES VINCENTHARRINGTON iheir ATTORNEYS Nov. 21, 1967 3,353,364

UNDERWATER WELL ENCLOSING CAPSULE AND SERVICE CHAMBER J. E. BLANDINGETAL l7 Sheets-Sheet 11 Filed April 26, 1962 INVENTORS JOHN E. BLANDING,

EDMUND C. TRAGESER 8| v JAMES VINCENT HARRINGTON their ATTORNEYS I2131967 7 J.E. BLAN'DING-ETALI. 3,353,364

UNDERWATER WELL ENCLOSING CAPSULE AND SERVICE CHAMBER Filed A ril 26,1962 17 Sheets-Sheet 12 Hat/7 INVENTO S JOHN E. BLANDING, EDMUND C.TRAGESER 8 JAMES VINCENT HARRINGTON 5 q P @MMZ their ATTORNEYS 21, 5 J.E. BLANDING ETAL 3,353,364

' UNDERWATER WELL ENCLOSING CAPSULE AND SERVICE CHAMBER Filed April 26,1962 17 Sheets-Sheet 15 MIN F/a/a INVENTORS JOHN E. BLANDING, EDMUND C.TRAGESER Bu JAMES VINCENT HARRINGTON I Jhe ir ATTORNEYS O 1957 J. E.BLANDING ETAL UNDERWATER WELL ENCLOSING CAPSULE AND SERVICE CHAMBERFiled April 26, 1962 INVENTORS JOHN E. BLANDING,

EDMUND C.TRAGESER a JAMES VINCENT HARRINGTON ,6 W their ATTORNEYS" 17Sheets-Sheet 14 Nov. 21, v1967 J. E. BLANDING ETAL 3,353,364

UND ERWATER WELL ENCLOSING CAPSULE AND SERVICE CHAMBER l7 Sheets-Shet 15Filed April '26, 1962 INVENTORS JOHN E. BLANDING,

EDMUND C-TRAGESER 7 BY JAMES VINCENT HARRINGTON I W, PW

ave-= their ATTORNEYS NOV. 21, 1967 BLANDmG L- 3,353,364

UNDERWATER WELL'ENCLOSING CAPSULE AND SERVICE CHAMBER Filed April 26,1962 17 Sheets-Sheet 16 INVENTORS JOHN E. BLANDING heir ATTORNEYS 1967J. E. BLANDING ETAL UNDERWATER WELL ENCLOSING CAPSULE AND SERVICECHAMBER Filed April 26, 1962 17 Sheets$heet 17 m F/G. 22-

INVENTORS JOHN E. BLANDING, EDMUND C.TRAGESER a JAMES VINCENT HARRINGTONtheir ATTORNEYS United States Patent Ofiice 3,353,364 Patented Nov. 21,1967 3,353,364 UNDERWATER WELL EN CLOSING CAPSULE AND SERVICE CHAMBERJohn E. Blanding, Old Lyme, Edmund C. Trageser, Norwieh, and JamesVincent Harrington, Mystic, Conn., assignors to General DynamicsCorporation, New York, N.Y., a corporation of Delaware Filed Apr. 26,1962, Ser. No. 193,040 16 Claims. (CI. 6169) The present inventionrelates to underwater drilling methods and apparatus and, moreparticularly, to novel methods and apparatus permitting a separation ofthe drilling, producing, and servicing phases of underwater wellconstruction and operation.

This is a continuation-in-part of our application Ser. No. 81,543, filedJan. 9, 1961, and now abandoned The rapid depletion of the naturalresources underlying the earths land masses and the growing demand forraw materials have led to an urgent quest to develop means forexploiting deposits beneath the floor of the sea and in other areasunderlying water. A number of devices have been developed for thispurpose, including notably the mobile platforms now in operation off thecoasts of the United States mainland. However, conventional mobileplatforms and similar apparatus have not provided a complete solution tothe problem.

It is an object of the present invention, accordingly, to provide newand improved means for drilling, operating and servicing wells under thewater.

A further object of the invention is to provide new and improved meansfor enclosing an underwater wellhead, keeping it dry, and enablingworkmen to gain access to it for well maintenance.

Still another object of the invention is to provide means for loweringworkmen to the wellhead for inspection and maintenance purposes.

Another object of the invention is to provide separate pieces ofequipment to accomplish the drilling, operating, and servicing ofunderwater wells, including means for drilling a well, a watertightcapsule for enclosing the wellhead, and personnel-carrying means forservicing the equipment at the wellhead at periodic intervals.

Another object of the invention is to make possible the replacement ofconventional platforms by a small underwater capsule which isinexpensive and undisturbed by weather and shipping.

These and other objects are attained, in a first representativeembodiment of the invention, by providing a submersible vessel which isoutfitted with the accouterments of the well driller. Attached to thevessels exterior surface is a watertight capsule adapted sealably topass drilling and easing means. Drilling means are extended from thevessel through the capsule for drilling a well, and casing is insertedinto the well and sealed to the capsule. When the well is completed, thecapsule and the vessel are sealed off from each other and separated. Thecapsule remains on the floor of the sea enclosing the wellhead andkeeping the equipment at the wellhead dry, and the vessel is availablefor drilling another well. At periodic intervals a service chamber maybe lowered to facilitate inspection and repair of the equipment at thewellhead. A line extending from the capsule to a float on the surface ora coded transponder on the capsule facilitates relocation of thecapsule.

A second embodiment of the invention has numerous features which adaptit particularly for shallow-water drilling. For example, means areprovided for mounting blowout preventers above the waters surface.

A third embodiment of the invention, adapted particularly for drillingin great water depths,has many novel features including novel hold-downequipment for holding down underwater-well apparatus. The apparatus soheld includes a plurality of submersible chambers mounted upon awellhead in vertically-stacked relation on a floor underlying water.

For an understanding of further particulars of the invention, referencemay be made to the following detailed description of threerepresentative embodiments thereof and to the accompanying figures ofthe drawings, in which FIGS. 1-6 illustrate the first embodiment, FIGS.7-13 the second, and FIGS. 14-22 the third. More particularly:

FIG. 1 is a perspective view, partially broken away, of a submersiblevessel supported by a foundation pad on a floor underlying water andsealably attached to a watertight capsule in accordance with a firstrepresentative embodiment of the invention;

FIG. 2 is a detailed view in elevation (partly sectioned along the line22 of FIG. 4) of the capsule as it appears when it is attached to thesubmersible vessel and has typical drilling equipment in place;

FIG. 3 is a detailed view in elevation (partly sectioned along the line3-3 of FIG. 4) of the capsule as it appears after completion of thewell, substitution of well-completion equipment for the drillingequipment, placement of a watertight hatch on the capsule, and departureof the submersible vessel;

FIG. 4 is a plan view, partially broken away, showing the constructionof the capsule-hatch seal;

FIG. 5 is a diagrammatic representation of a service chamber beinglowered from a tender to the capsule at the wellhead for the purpose offacilitating inspection or repairs in accordance with the invention;

FIG. 6 is a view in elevation, partially broken away, of the servicechamber in position on top of the capsule and forming a watertight sealtherewith;

FIG. 7 is a perspective view of apparatus for lowering a capsule supporteasing into a conductor pipe driven or otherwise placed into ashallow-sea floor in accordance with the invention;

FIG. 8 is a partly-sectioned elevational view of a drilling capsuleparticularly suited for drilling in relatively shallow water;

FIG. 9 is a partly-sectioned fragmentary elevational view of themechanism by which the watertightintegr'ity of the capsule shown in FIG.8 is established along an annular junction of upper and lower halves ofthe capsule and by which the upper half is guided into sealing relationwith the lower half; 1

FIG. 10 is a partly-sectioned detailed elevational view of one form ofadaptor constructed in accordance with the invention;

FIG. 11 is a vertical sectional view of a wellhead and associated meansconstructed in accordance with the invention for hanging a plurality ofcasings down into a well during a drilling operation and for supportinga plurality of upper casing extensions associated therewith;

FIG. 12 is a partly-sectioned elevational view of a production capsuleparticularly adapted for use in relatively shallow waters;

FIG. 13 is a partly-sectioned fragmentary elevational view of ahydraulic lifting device shown also in FIG. 12;

FIG. 14 is a diagrammatic view of an overall arrangement of capsule,adaptor, separating equipment, production buoy, underwater storage tank,surface vessel and other apparatus particularly adapted for usein'connection with wells drilled in great depths of water;

FIG. 15 is a partly-sectioned elevational view of a conductor pipe and afoundation pad which are being prepared at great depth to receive adrilling capsule;

FIG. 16 is a partly-broken-away and partly-sectioned I elevational viewof a capsule enclosing a wellhead on the floor of the sea, the structurebeing particularly adapted for use in drilling in great depths of water;

FIG. 17 is a partly-sectioned elevational view of a deep-water capsulehaving well-completion valves in place and hydraulically-operatedhold-downs from a superior chamber inserted in hold-down tubes attachedto the capsule;

FIG. 18 is a partly-sectioned elevational view of a novel adaptor foruse with the capsule shown in FIG.

cordance with the invention;

FIG. 21 is a partly-sectioned elevational view of a center-line elevatoror submersible personnel chamber constructed in accordance with theinvention; and

- FIG. 22 is a partly-sectioned elevational view of a production buoyconstructed in accordance with the invention.

While for purposes of exposition the three embodiments are treatedseparately, various apparatus and methods described in connection withone embodiment may also be used in combination with apparatus andmethods which are described as relating to another embodiment.

First embodiment: Drilling a well from a submersible vessel In FIG. 1 asubmersible vessel '10 is shown permanently secured to a foundation pad11 at the bottom of the sea by remotely-controlled vertical adjustors13. As many adjustors are used as may be necessary, and, in any event,other adjustors similar to the ones shown are locatedon the side of thevessel opposite the side visible in the figure, so that the vessel 10 isprovided with at least four legs formed in a manner hereinafter setforth to hold down the vessel 10 and make final adjustments in itsposition when it arrives at the bottom.

The adjustors 13 are permanently attached to the vessel 10 and comprisecylinders 13a fitting sealably about rams 13b slidably mounted therein.Ram extensions 130 which extend downwardly from the rams 13b andsealably through the bottoms of the cylinders 13a to form .the legsjaresecured to the pad 11 by ball-in-socket connections 13e or other(preferably universal) connections. Fluid lines 13d communicate withopposite ends of the cylinders 13a and extend to conventional apparatus(not shown) mounted within the vessel 10 for supplying a fluid to andexhausting it from the cylinders 13a, so that the' ram extensions 130may be remotely moved upwardly or downwardly to provide proper controlof the position of the vessel 10.

A capsule 14 extending through a hole 15 in-the pad 11 forms awatertight seal at its upper end with the vessel 10 by means of amechanism indicated generally at 16, hereinafter described in detail,and at its lower end with .a well casing 17.

Inasmuch as the pad '11 may settle during the drilling operation, it maybe necessary to adjust the position of the vessel 10 with respect to thepad 11 by means of the adjustors 13 in order to preserve the seals atthe end of the capsule 14. Relative vertical movement of the vessel 10with respect to the pad 11 is readily elfected by equal parallelmovements of the ad justors 13. Limited horizontal movement of thevessel 10 with respect to the pad 11 is efiected by certain unequalmovements of the adjustors 13.

' Lugs 18 help to establish the proper orientation of the capsule 14with respect to the vessel 10 and thereby facilitate the forming of theseal by means of the mechanism 16. The lugs 18 are conveniently three innumber and spaced at -degree intervals around the periphery of thecapsule 14.

A traveling block 20 is used to lower a kelly 21, a drillpipe (not shownin FIG. 1), and the casing 17 into the capsule 14 and sealably throughsealing means such as locks (not shown) in the bottom thereof.

FIG. 2 shows in detail the structure of the capsule 14 and the equipmentassociated therewith during the drilling process. The top 22 of thewellhead 23, which is securely mounted in and tightly sealed to thecapsule 14, supports a double cellar gate 24 having a lower gate 25 andan upper gate 26. In accordance with the custom of the art, the cellargate 25 is fitted with pipe rams (not shown), while the cellar gate 26is fitted With blind rams (not shown). An annular preventer 27 isremovably mounted on the double cellar gate 24, and an extension spool28 extends upwardly from the top 29 of the preventer 27 for engagementwith a drill-through blowout preventer 31.

The drill-through blowout preventer 31 comprises a lower stationary bodyportion 32 and an upper or stripper portion 33, also stationary. Whiledrilling is in progress, the kelly 21 is slidably and rotatably attachedto the stripper portion 33 and extends downwardly through the portion 32for engagement with a drill pipe 34 which drives a drill bit (not shown)at its lower end.

In accordance with standard drilling practice, all of the blowoutpreventers, including any additional preventers mounted between theextension spool 28 and the preventer 31, are remotely controlled, anddrill bits and casing are passed or locked through the preventers andinto the floor of the sea.

Mud return is provided for in the usual manner by an emergencyhigh-pressure outlet 35 on the wellhead 23 which communicates through avalve 36 with a high-- pressure mud-return line 37 and by anormal-pressureoutlet 38 on the preventer 31 which communicates througha valve 39 with the high-pressure mud-return line 37 to form acombined-pressure mud-return line 40.

A closure plate 41, which is sealed to a flange 42 on the vessel 10 bymeans of bolts 43 and annular packing 44, prevents the entry of seawaterinto the interior of the vessel 10 in the event that the sealestablished by means of the mechanism 16 between the vessel 10 and thecapsule 14 becomes ineflective during the drilling operation. A firstopening 45 in the plate 41 is fitted with a removable gland 46, whichforms a slidable seal about the spool 28. A second opening 47. in theplate 41 is fitted with a removable gland 48, which forms a seal aboutthe high-pressure mudreturn line 37. A manhole 49, the third and finalopening in the plate 41, is provided with a cover 50, which is tightly.sealable about its periphery to the plate 41.

The watertight seal between the vessel- 10 and the capsule 14 iseffected by a circular flange 42 on the vessel 10 and a. mating flange51 on the capsule 14 which are wedded .by the mechanism 16 referred toabove. The mechanism 16 includes a level 52 for turning a shaft 53 atthe end of which a pinion 54 engages a ring gear or annulus 55. Theannulus 55 has a dovetail circular tongue 56 which fits within adovetail circular groove 57 in the bottom of the vessel 10 so that theannulus can be freely rotated. When the annulus 55 is rotated,spaced-apart inwardly projecting lips 58 on the annulus engagespaced-apart. outwardly projecting lips 59 formed around the circum--ference of the flange 51. The. lips '58 and 59 are inclined.

to form portions of helices, so that the vessel 10 and capsule 14 aredrawn tightly together when the annulus 55 is rotated in one directionand are disengaged from each other when the annulus is rotated in theopposite direction. Suitably placed packing or gaskets at 60, '61 and 62ensure a watertight seal. A collar 63 on the shaft'53 maintains thevertical position of the shaft regardless of the pressure of the sea.

Thus it will be seen that drilling can be conveniently accomplished fromthe submerged vessel by personnel who are not subjected to the hazardsof working while exposed to the great pressures which prevail in theocean depths.

After the drilling of the Well is completed the welldrilling equipmentis removed from the capsule 14, well production equipment is put inplace, a hatch 64 is put onto the capsule 14, and the vessel 10withdraws; see FIG. 3. The cementing of the casing 17 may beaccomplished in a conventional manner.

The well completion equipment illustrated in FIG. 3 includes a Christmastree 65 which has one or more master valves 66 and wing connections 67and 68 which pass sealably through the capsule 14 for the delivery ofoil. Wing valves 69 and 70, respectively, control the flow of oilthrough the wing connections 67 and 68 and sea valves 71 and 72 so thateither of the wing connections can be closed off to facilitate themaking of repairs.

The watertight integrity of the capsule 14 in the vicinity of the hatch64 is maintained by a circular sealing flange 73 on the hatch whichmates with the sealing flange 51 on the capsule. The flanges are lockedtogether by means of a wheel 74 which rotates a shaft 75 connected torods 76. When the wheel 74 is turned the rods 76 are rotated about theaxis of the shaft 75 so that their outer ends fit into slots 77. Theslots 77 are inclined to form portions of helices, so that the hatch 64and capsule 14 are drawn tightly together when the wheel 74 is rotatedin one direction and are disengaged from each other when the wheel isrotated in the opposite direction. Packing 78 ensures a watertight seal.See also FIG. 4, which is a plan of the capsule 14 and hatch 64.

A downhaul cable 79, illustrated in FIGS. 3 and 5, extends verticallyfrom the hatch 64 to the surface of the water, where it may be securedto a float (not shown) indicating the position of the well. The floatmay be distinctively marked to identify a particular well in a field.Alternatively, a transponder 79a on the capsule 14 may be used for thispurpose. The transponder 79a may be coded to transmit an identifyingsignal on demand.

FIG. 5 ShOWs a service chamber 80 guided in its descent from a tender 81to the capsule 14 by the downhaul cable 79, which is taken up within thechamber 80 on a cable reel 82 (see FIG. 6). Cables 83 include air supplyand exhaust hoses and light and communications lines. Anchor chains 84and 85 hold the tender 81 in position during the descent of the chamber80 (FIG. 5).

When the chamber 80 reaches the capsule 14, (FIG. 6) it is guided by thedownhaul cable 79 and the lugs 18 so that it is properly oriented withrespect to the capsule 14. A gasket 86 corresponding to the gasket 62 onthe vessel 10 is compressed by the chamber 80 to form a temporary seal.

In FIG. '6 the chamber 80 is illustrated in position on top of thecapsule 14. The chamber 80 comprises an upper compartment 87 and a lowercompartment 88 divided by a deck 89. The upper compartment 87 is of awatertight construction, while the lower compartment 88 has a divingbell configuration: That is, it is enclosed on the top and around thesides but open at the bottom during the descent of the chamber 80.

The personnel who are to effect repairs within the capsule 14 make thedescent in the compartment 87 (to which they gain access through anupper hatch 90 while the chamber 80 is on the surface) and areaccordingly exposed to a pressure of only one atmosphere. Thecompartment 88 admits water at the bottom as the chamber 80 makes thedescent. The water is, of course, unable to rise completely to the topof the compartment 88 but compresses into the upper portion thereof theair trapped therein, keeping it always at the pressure of the water 6 atthe depth at which the chamber happens to be located.

A pump 91 is provided to expel the water from the compartment 88 througha valve 92 and into the sea after the chamber 80 is seated on thecapsule 14. The air trapped within the compartment 88 simultaneouslyexpands and fills all of the compartment except the part thereof whichis now occupied by the upper portion of the capsule 14. Thus, with theremoval of the water from the compartment 88, the pressure within thecompartment is reduced to little more than one atmosphere. Venting thelower compartment 88 to the upper compartment 87 equalizes the pressuresin the two compartments.

If the chamber 80 is accidentally tipped while being lowered into theWater, so that the compartment 88 prematurely fills with water, air isadmitted into the compartment 88 after a temporary seal has beenestablished between the chamber 80 and the capsule 14 by means of thepacking 86 and during the time when the Water in the compartment 88 isbeing pumped out into the sea in order to fill the vacuum which iscreated in the compartment 88 upon the removal of the water. The air tofill the vacuum is supplied from the compartment 87 or tanks (not shown)of compressed air.

After the pressure in compartment 88 has been brought to the properlevel, a hatch 94 in the deck 89 may safely be opened by means of ablock-and-tackle 95, and the personnel within the compartment 87 maydescend into the compartment 88. Here they may complete the formation ofa watertight seal between a circular flange 96 (identical to the flange42 on the vessel 10) and the flange 51 by means of a mechanism 97(identical to the mechanism 16 on the vessel 10) in the manner describedabove, open the hatch 64 and descend into the capsule 14 for the purposeof making an inspection or etfecting repairs. Upon completion of theinspection or repairs they may reenter the compartment 88, replace thehatch 64 on the capsule 14, break the seal between the flanges 96 and 51by means of the mechanism 97, re-enter the compartment 87, replace thehatch 94 in the deck 89, admit water into the compartment 88 to raisethe pressure therein, and signal the personnel on the tender 81 that thechamber 80 is returning to the surface. A cable 98 is reeled in as thechamber 80 rises.

Second embodiment: Drilling at well in shallow water FIGS. 7 through 13illustrate an embodiment of the invention particularly adapted for usein drilling, completing and producing from a well in shallow waters.Water is deemed to be shallow for present purposes when drilling may beaccomplished from a platform which is mounted on a floor underlyingwater but which extends above the waters surface.

FIG. 7 shows means for lowering casing into an underwater well. Aconductor pipe 100 has been driven by conventional means into the floorof the sea to the point of refusal in preparation for drilling a well.An anchor pad 101, having casing-means-receiving means such as a centerhole 102 large enough to pass over the conductor pipe 100, is loweredabout the conductor pipe 100 in concentric relation thereto. Elongatedguide means such as guide cables 103 attached to the anchor pad 101 onopposite sides of the hole 102 by conventional releasable end fittings104 extend upwardly to a drilling rig (not shown) on the surface of thewater. The drilling rig may be a conventional rig mounted on a platformresting on the bottom of the sea and rising above the waters surface.

A hole or well is drilled to a desired depth (which may be a thousandfeet or so) below the lower end of the conductor pipe 100, so that thehole 102 is aligned with the well, and the conductor pipe 100 is thensevered in the vicinity of the pad 101 at, say, a point 105, the upperportion being withdrawn to the drilling rig, where it may be stored forlater use on another Well. A capsule-support casing 107 also carriedaboard the drilling rig is then

1. APPARATUS FOR ENCLOSING AN UNDERWATER WELLHEAD, COMPRISING A LOWERCAPSULE PORTION HAVING AN UPPER RIM, AN UPPER CAPSULE PORTION HAVING ALOWER RIM REMOVABLY ATTACHABLE IN SEALED RELATION TO SAID UPPER RIM,WHEREBY SAID PORTIONS FORM A HOLLOW WATERTIGHT CAPSULE, BIASING MEANSMOUNTED ON ONE OF SAID RIMS AND ADAPTED TO EXERT A FORCE AGAINST ONESIDE OF THE OTHER OF SAID RIMS, BRACKET MEANS MOUNTED ON SAID ONE OFSAID RIMS AND CO-OPERATING WITH THE OTHER SIDE OF THE OTHER OF SAIDRIMS, AND CHAFING MEANS MOUNTED ON SAID OTHER OF SAID RIMS ANDINTERPOSED BETWEEN SAID OTHER OF SAID RIMS AND SAID BRACKET MEANS, SAIDCHAFING MEANS, SAID BRACKET MEANS AND SAID BIASING MEANS CO-OPERATING TOGUIDE SAID RIMS INTO SAID RELATION.
 2. A SERVICE CHAMBER COMPRISING AHOLLOW WATERTIGHT UPPER COMPARTMENT, A LOWER DIVING-BELL COMPARTMENT,ANNULAR SEALING MEANS FORMED ABOUT THE INTERIOR OF SAID LOWERCOMPARTMENT, WHEREBY SAID LOWER COMPARTMENT MAY BE SEALED TO A SEALINGNECK INSERTED THEREWITHIN, A PAIR OF RELATIVELY MOVABLE JAWS CONNECTEDTO SAID CHAMBER, AND BIASING MEANS FOR URGING SAID JAWS INTOCO-OPERATIVE RELATIONSHIP, SAID JAWS BEING ADAPTED TO CO-OPERATE WITHEACH OTHER AND WITH AN ELONGATED MEMBER EXTENDING BETWEEN AN UNDERWATERWELL AND THE SURFACE OF THE WATER FOR GUIDING SAID CHAMBER DURINGMOVEMENT FROM THE SURFACE OF THE WATER TO AN UNDERWATER WELL.